Average Surface Pressure Research Articles

Surface properties of muscle protein extracts

The interfacial properties of proteins extracted from muscle using salt solutions of different concentration and for different extraction times were determined by the drop volume method. At a bulk phase concentration of 10 −2 wt%, it appears that the sarcoplasmic-rich fraction of muscle is more surface active than the salt-soluble fraction. The average equilibrium surface pressure at the air-liquid interface was 21·5 mN m −1 for an aqueous extract and 20·1 mN m −1 for a 1 m KCl-extract. The equilibrium surface pressure decreased from 21·7 mN m −1 to 19·50mN m −1 as the extraction time with Weber-Edsall solution increased from 15 min to 48 h.

Geology of Sweet Lake Geopressured-Geothermal Prospect, Cameron Parish, Louisiana--Drilling and Testing Results: ABSTRACT

ABSTRACT The Sweet Lake geopressured-geothermal well is located in a basin on the north flank of an east-west trending salt ridge that includes the Hackberry, Big Lake, and Sweet Lake structures. The south side of the basin is bounded by a fault downthrown to the north. This fault converges eastward with a major east-west trending fault which is downtown to the south. The two faults form a graben which terminates to the east by the convergence of the faults and is open to the west. Within the basin the primary geopressured-geothermal aquifer is the Miogypsinoides sand of the Camerina zone (Upper Frio Formation of Oligocene-Miocene age). Within the graben sediments dip northwest into the basin with dip angles as high as 20°. The first Miogypsinoides microfossil was picked at 14,970 feet, and the first good sand occurred at 15,065 feet. The sequence is 640 feet thick (15,000-15,640), with 250 feet of net sand. There are seven potentially productive sands within the sequence. Four diamond cores were taken. Data from Core no. 3, 15,389-15,405 indicated the sands are medium- to fine-grained, with 1-2% silt-sized material. Median grain size is .26mm. Thin sections parallel and perpendicular to the core axis show the grains to be angular to sub-angular. X-ray analysis showed 75% quartz, 19% feldspar, 4% illite, 2% mixed-layer clay (illite/smectite), and a trace of kaolinite. SEM photographs showed cement as quartz overgrowths and clay as very fine hairs in the pore spaces. Porosity is 24% and permeability 3600 md. in Core no. 3, the fifth sand in sequence. Initial reservoir pressure in this perforated zone (15,387-15,414) was 12,060 psi. Temperature at the mid-point in the sand was 299°F. The calculated SP salinity for the well was 50,000-70,000 ppm. If Rw/2 is used instead of Rw, the calculated salinities increase to 125,000-140,000 ppm. Reservoir testing included draw-down and build-up tests. The well was flowed a total of 240 days. Flow rates varied from 1,000 bb1/day to 34,000 bb1/day. Average surface pressure during the testing is 2500 psi. The gas-water ratio is 25-28 SCF/B, of which 20 SCF/B are recovered. Additional testing of the reservoir is planned.

Studies on the surface structure of very low density lipoproteins

Very Low Density Lipoproteins (VLDL) were incubated with 5 different pure phospholipases. From the results the following conclusions were drawn. 1. (1) The phospholipids are localized in a monomolecular layer on the outside of the VLDL particles. This supports the lipid core model proposed by several groups. 2. (2) A minor fraction of the phospholipids (ranging from 3 to 10%) cannot be degraded by the enzymes and probably have a strong interaction with apoproteins. 3. (3) The average surface pressure of VLDL is probably low, and comparable with a lateral surface pressure of 15 dynes/cm at the air-water interface, as concluded from experiments with two phospholipases A 2. Calculations of the thickness of the surface coat and protein coverage on the basis of this value agree very well with values reported in literature.

Infrared heterodyne spectroscopy of CO 2 in the atmosphere of Mars

An infrared heterodyne spectrometer with a resolving power of 6 × 10 6 has been used to obtain detailed profiles of the 10-μm absorption lines of CO 2 in the atmosphere of Mars. An analysis of the results with an empirical model atmosphere calculation indicates a nearly pure CO 2 atmosphere with an average surface pressure of 5.2 ± 0.5 mbar in the observed regions, a subsolar surface temperature near 275°K, an atmospheric temperature of 235 to 240°K above the subsolar point, and a lapse rate of 2°K/km.

Polar Volatiles on Mars—Theory versus Observation

The residual frost caps of Mars are probably water-ice. They may be the source of the water vapor associated with seasonal polar hoods. A permanent reservoir of solid CO(2) is also probably present within the north residual cap and may comprise a mass of CO(2) some two to five times that of the present atmosphere of Mars. The martian atmospheric pressure is probably regulated by the temperature of the reservoir and not by the annual heat balance of exposed solid CO(2) (37). The present reservoir temperature presumably reflects a long-term average of the polar heat balance. The question of a large permanent north polar cap is reexamined in light of the Mariner 9 data. The lower general elevation of the north polar region compared to the south and the resulting occurrence in the north of a permanent CO(2) deposit are probably responsible for the differences in size and shape of the two residual caps. The details of the processes involved are less apparent, however. It might be argued that the stability of water-ice deposits depends on both insolation and altitude. The present north and south residual caps should be symmetrically located with respect to such a hypothetical stability field. However, the offset of the south cap from the geometrical pole, the non-symmetrical outline of the north cap, and the apparently uniform thickness of the thin, widespread water-ice all argue against control by simple solid-vapor equilibrium of water under present environmental conditions. We think that the present location of the water-ice may reflect, in part, the past location of the permanent CO(2) reservoir. The extreme stability of polar water-ice deposits increases the likelihood that past environmental conditions may be recorded there. Detailed information on elevations in the vicinity of the residual caps is needed before we can further elucidate the nature and history of the residual caps. This, along with measurements of polar infrared emission, should be given high priority in future missions to Mars. Two conclusions follow from the limitation of the mass of solid CO(2) on Mars at present to two to five times the mass of CO(2) in the atmosphere. If all of this CO(2) was entirely sublimated into the atmosphere as a result of hypothetical astronomical or geophysical effects, the average surface pressure would increase to 15 to 30 mbar. Although such a change would have considerable significance for eolian erosion and transportation, there seems to be little possibility that a sufficiently earthlike atmosphere could result for liquid water to become an active erosional agent, as postulated by Milton (38). The pressure broadening required for a green-house effect requires at least 10 to 20 times more pressure (39). If liquid water was ever active in modifying the martian surface, it must have been at an earlier epoch, before the present, very stable CO(2)/H(2)O system developed. There can be no intermittent earthlike episodes now. Furthermore, the present abundance of CO(2) on Mars may be an indicator of the cumulative evolution of volatiles to the surface of the planet (40). Thus, even the possibility of an earlier earth-like episode is dimmed. On Mars, the total CO(2) definitely outgassed has evidently been about 60 +/- 20 g/cm(2). On the earth, about 70 +/- 30 kg/cm(2) of CO(2) have been released to the surface (41). Hence, the total CO(2) devolved by Mars per unit area is about 0.1 percent of that evolved by the earth. Thus, the observational limits we place on solid CO(2) presently located under the north residual cap also may constitute considerable constraints on the total differentiation and devolatilization of the planet. If they are valid, it would seem unlikely that Mars has devolatilized at all like the earth, or ever experienced an earthlike environment on its surface.

Venus: Estimates of the Surface Temperature and Pressure from Radio and Radar Measurements

The radio brightness temperature and radar cross section spectra of Venus are in much better accord with surface boundary conditions deduced from a combination of the Mariner V results and the radar radius than those obtained by the Venera 4 space probe. The average surface temperature and pressure are approximately 750 degrees K and 90 atmospheres.

Field Results of the Stressed Steel Liner Casing Patch

Kemp, Gore, Member AIME, Davis-Kemp Tool Co., Inc., Kilgore, Tex. Abstract The stressed steel liner was developed to reduce rig and tool costs over the more conventional methods of repairing casing leaks. A steel tube, corrugated to reduce its diameter, is run into the well opposite the leak; by means of a hydraulically operated ram, it is expanded into place forming a leak-proof sleeve. Eighty-two patches have been installed in wells with a success of 89 per cent. Rig requirements and time involved have been reduced, as well as tool costs. The method has been used successfully to seal leaks, perforations, splits and parted casing. It is particularly applicable for use in small-diameter casing. Introduction Casing leaks constitute one of the most critical and costly problems encountered in the maintenance of oil production. This is particularly true in the older fields, where corrosion and electrolysis are causing an ever-increasing incidence of the problem. These older fields usually cannot afford costly workovers due to low production and high lifting costs. Development of a method of casing repair that would be quicker and less expensive than the conventional cement-squeeze or the casing-cutoff and patch-bowl methods has been a continuous process for several years. The glass fabric-plastic casing patch was developed in 1958–59 and was used for several years with reasonable success. This method had serious limitations, however, when the hole in the casing was large or when the pipe was split. It was not a satisfactory cure for parted casing. The depth of the casing leak may be found by any ac- of the plastic patch, and it was first used in a well in July, 1961. This paper describes the tools which have been developed for field use and presents the results of 82 consecutive jobs in a five-state area. Process And Tools The depth of the casing leak may be found by any accurate method, but best results have been obtained by using straddle packers or bridge plug and packer. and then pressuring between them. If wireline methods of measurement are used, it is necessary to check this with pipe measurements because field experience has taught that considerable variation exists between the two methods. An impression of the damaged area of casing may be made in order to more clearly define the size and type of the leak. Fig. 1 shows impressions taken with a sheet of vinyl on the right and uncured rubber on the left. An impression is made by attaching the material to an inflatable bladder, placing the tool opposite the damaged area, and inflating it to a pressure of 200 to 300 lb. The embossed impression material provides accurate size measurement and identifies extreme damage-such as splits and parted casing. After the depth and the extent of damage having been determined, the casing is thoroughly cleaned with a conventional casing scraper. A gauge ring should be run to make sure that no collapse or other damage is present to obstruct the casing. To reduce rig time as much as possible, the tubing is usually pressure-tested at this point to be sure that no failure will occur while the liner is being installed. Since the average surface pressure required to place the liner is 2,400 psi, the tubing or working string is usually tested to 5,000 psi. The patch itself consists of a mild steel tube which varies in wall thickness from 0.065 in. as used in 2 7/8-in. OD casing to 0.125 in. which is used in 5 1/2-in. OD and larger casing. This tubing is first annealed, and then its diameter is decreased by pulling it through a series of rollers to corrugate it. The tube is again annealed to relieve the stresses set up when it is corrugated. JPT P. 147^